The more precursors we find, and the more specific they seem to be — so that their functions in multicellular organisms would not be easily replaced by other components — the more difficult it is to accept a non-teleological origin.

IOW, if a gene vital in multicellular life forms is present and highly conserved in single-cell life forms (in which it isn't expressed or perform any other vital function), we could conclude that the gene was front-loaded into the genome by a designer of the original genome with the expectation that multicellular life forms would evolve when that gene does get expressed.

However, almost as soon as multicellularity arose, it "exploded", producing the fantastic diversity of multicellular animals, plants, and fungi that we see today and in the fossil record of the Phanerozoic.